Common plastic bag styles used by retailers in fast food chains, supermarkets, and general merchandise, as well as certain point-of-purchase applications, are typically of the bottom seal or sideweld variety. These bags are usually gusseted along their sides or along the bottom with the open bag mouth at the top. Many of these common bags have carrying handles for customer convenience, which are usually of the strap variety or die-cut holes. Typical plastic bags used in supermarket applications are about 0.0005 to 0.00065 in gauge; those used as fast food bags are usually from 0.0007 to 0.00125, and; those used in point of purchase applications may be anywhere from 0.0005 to 0.004 millimeters of thickness. Retailers that desire to have a bag that allows for easy gas and vapor transmission usually use paper bags instead of plastic bags, since plastic serves as a virtually non-porous barrier which does not readily allow vapor or gas transmission. Two excellent examples in which moisture vapor and gas transmission is important is in a hot foods application such as hot French fries, or in a baking applications such as sourdough bread and bagels (the outer crust must maintain a certain hardness). In both of these applications, the French fries or the bread products, the foods will become soggy and generally lose customer appeal if plastic bags are used. Large fast food chains, such as McDonald's and Burger King, continue to use paper bags for carry out due to this factor. And virtually all sourdough and all fresh-made bagel companies also prefer paper to retain the hard outer crust. Many other similar food applications, such as crispy or crunchy cookies, or certain vegetables such as cauliflower and lettuce, also require ventilation. In food applications with fruits and vegetables, they will require adequate ventilation to prevent the growth of molds or fungi. In certain other applications it is desirable to have a vented package in which certain gases may enter a bag in order to help preserve the food product contained within while being transported or being stored, which extends shelf life.
Ventilating plastic film is well known in the art. In U.S. Pat. No. 3,762,629 Bruno reveals a lattice network on a plastic sheet that has been commonly used as lettuce wrap. In his U.S. Pat. No. 4,709,400 Bruno also reveals vented bags with ties which may be used for bundling fruits such as grapes. Micro-perforations are also commonly used in some bakery applications as well as some vegetable and fruit uses such as that illustrated in U.S. Pat. No. 5,171,593, Doyle. In U.S. Pat. No. 5,362,152, Fletcher, et al, reveal a T-shirt bag which has "C-shaped" vent holes which, allow for air ventilation in hot food applications. As is well-known in the art, there are various means of controlling the amount of air ventilation, such as using fillers and additives to the film, adding moisture absorbent packets inside bags and so on. These means of control increase the cost of a bagged product substantially and would typically be impractical for the high volume, mass merchandise, carry out food, bakery, or produce related businesses such as fast food restaurants or in many supermarket produce and bakery applications.